Recent studies on real driving emissions of diesel passenger cars

Real driving emissions (RDE) from passenger cars has come under close scrutiny in recent times due to a perceived divergence between stated certification and measured on-road performance. This has been most pointed in the case of NOx emissions from diesel cars. To build understanding of the emissions performance of the latest available diesel passenger cars, Concawe asked Ricardo consulting engineers to conduct a study on the ‘Expectations for actual Euro 6 vehicle emissions’ and to carry out Concawe work involving a study of the chassis dynamometer (CD) and RDE performance of three Euro 6b+ vehicles.

As well as having diesel particulate filters (DPFs), two of the vehicles featured high- and low-pressure exhaust gas recirculation (EGR) and aqueous urea-dosed selective catalytic reduction (SCR) aftertreatment systems, while the third used high pressure EGR and was fitted with a lean NOx trap (LNT). For each vehicle, tests were conducted over RDE, WLTC, NEDC and US06 cycles. Both studies provide insight into the on-road emissions performance of the latest diesel passenger cars, and into how this compares with regulated emissions limits and results from CD tests run under comparable conditions.